The invention relates to a scraper for chains in chain conveyors, particularly for use underground, with a lower part which can be bolted to an upper part, the two parts each bearing one part of one or more chain beds through which a level dividing plane passes, as well as each bearing one part of the recesses provided for the bolts located outside the chain bed, where the upper and the lower parts at least partly interlock.
This type of two-part scraper has the important advantage that the straps required for attaching the chains to other scraper construction forms are not required here, and that the upper and lower parts are easier to handle than one-piece scrapers. This is particularly significant for underground operation, since the chain conveyor frequently has to be assembled at the face or in the immediate vicinity of the site where it is to be used, under correspondingly difficult conditions. On the other hand, the straps mentioned above have the advantage compared with the chain bolts which are used equally frequently that longer lengths of chain can be used between the scrapers, being known for this reason as long-length chains.
The scrapers of the design described in this introduction are divided along several planes which lie generally perpendicular to each other; the bolts are arranged horizontally and perpendicular sections of the dividing planes pass through the recesses for these in the scrapers. Due to this path of the dividing plane, the upper part and the lower part also interlock, which ensures that there can be no separation of the two parts under the effect of the bending forces acting on the scrapers.
However, the known scraper construction does not take into account the considerable amount of wear to which such scrapers are subjected due to the fact that they rest on the floor and the lateral guides of the conveyor trough. In fact, due to the described path of the dividing plane, the two end sections of the scraper are formed one on the upper part and one on the lower part of the scraper, and therefore with corresponding wear the whole scraper has to be changed. The known type of division also produces additional wear due to the fact that the main stressing of the scraper is caused by forces which act on its ends, so that, bearing in mind the tolerances which arise through the forging of the scraper halves, premature wear of the bearing surfaces on the upper and lower parts where these touch the dividing plane also arises.
Attempts have certainly already been made to counteract the wearing of the scrapers. With one-piece scrapers the said chain straps have had plastic strips or shoes fitted on their end faces in order thus to avoid frequent replacement of the scrapers. However, these measures cannot be applied directly to two-part scrapers, which are more advantageous for the reasons given in this introduction, and they would also not prevent the wear due to the tolerances in two-part scrapers.